those are heat exchanger protectors. I don't believe they were stock on any of the proaction sleds, but yamaha did make these, as well as many other brands. Is there a part number on yours? Mine are replicas of the venture ones Yamaha used to sell, and there is still room after the .92 track, and studs. If you don't have a venture, youa re in luck as the HX protectors are easily had for 35 dollars or so new. Unfortunately the venture used completely different front protectors. I tried 2 brands of ones that would fit SX, and other proaction chassis and those would not fit, not even the yamaha ones.
A 1.25 ripsaw will fit but not with studs as I mentioned.